The introduction of surgical staplers has greatly facilitated the art of closing the tissue of surgical patients and, in particular has greatly decreased the time required by the surgeon to Perform this task. Several useful versions of such devices are now known such as those disclosed in U.S. Pat. Nos. 4,608,981 issued to Rothfuss et al. on Sept. 2, 1986; 4,633,874 issued to Chow et al. on Jan. 6, 1987; and 4,892,244 issued to Fox et al. on Jan. 9, 1990.
The design of present staplers reflect the desire for speed and efficiency. Accordingly, such staplers commonly are designed in two pieces wherein the pieces may be separated to accommodate the insertion of a disposable staple cartridge and allow the user to quickly reload the device during a surgical procedure. Typically, one piece contains the staple cartridge including staples having sharp ends and the other piece includes an anvil against which the staple ends are clinched when tissue is being stapled. If the first and second pieces are not mated during stapling then the staple ends will not be clinched against the anvil. As a result patients will have sharp staple ends projecting upward from their tissue. This potentially dangerous situation illustrates how important it is for the first and second pieces to be mated when staples are being ejected.
In recognition of this problem, mechanisms to lock the mated first and second pieces have been devised. Unfortunately, Present locking mechanisms for linear staplers that are divided longitudinally into first and second pieces do not insure that the first and second pieces are mated when staples are being ejected.
One such stapler, described in U.S. Pat. No. 4,633,874, includes a pivotable C-shaped member affixed to a first piece and a stationary locking pin affixed to a second piece. The C-shaped member is pivotable between a first and a second position and engages and disengages the locking pin when moved into said respective positions to lock and unlock the two pieces.
While this locking mechanism, when engaged, will lock the two pieces together, it does not insure that the first and second pieces are mated when staples are being ejected because staples may be ejected whether the C-shaped member is in the first (unlocked) position or the second (locked) position. Accordingly, if the locking mechanism becomes disengaged during use or if the user neglects to engage the mechanism prior to use then, disadvantageously, staples may still be ejected from the unlocked stapler.
Consequently, there is a need for a two-piece surgical stapler, having locking means that insure that the first and second pieces are mated when staples are being ejected.